1. Field of the Invention
The present invention relates to an image pickup system and a communication system for use in, e.g., a video conference system for communicating at least image data and voice data between remote places.
2. Related Background Art
FIGS. 1A to 1C are schematic views showing a conventionally known video conference system. FIGS. 1A, 1B, and 1C illustrate the first, the second, and the third states, respectively. Referring to FIGS. 1A to 1C, a plurality of participants or attendants in a conference, for example, four persons A to D in a distant place are generally denoted by reference numeral 1. A television (TV) camera 2 for imaging the attendants 1 at the conference is placed on a panhead (not shown) for panning the TV camera 2. A camera control device 5 is so arranged as to freely change the panning position of the TV camera 2. A moving image codec 3 codes a video signal obtained by the TV camera 2. A communication control unit 4 supplies the coded video signal from the moving image codec 3 and other control information to a local line 6. A communication control unit 7 receives the coded video signal and the other control information from the local line 6. A moving image codec 10 decodes the coded video signal received by the communication control unit 7 and supplies the decoded video signal to a TV monitor 12. Each participant in the conference is displayed as a FIG. 13 on the TV monitor 12.
A camera operation unit 8 supplies a control signal to the camera control device 5 via the communication control unit 7, the local line 6, and the communication control unit 4, thereby panning the TV camera 2.
Of the above components, the TV camera 2, the moving image codec 3, the communication control unit 4, and the camera control device 5 are arranged in a remote place, and the communication control unit 7, the moving image codec 10, the TV monitor 12, and the camera operation unit 8 are arranged in a self-station which communicates with the distant place through the local line 6. In FIGS. 1A to 1C, for the sake of simplicity in explanation, only parts for imaging the attendants 1 are illustrated on the remote place side, and only parts for displaying the image are illustrated on the self-station side. The system, however, of course includes a voice system, a data system, and various operation systems in addition to the above components.
The operation of the above arrangement will be described below.
Assume, as shown in FIG. 1A, that the person B of the attendants 1 at the conference is imaged at the center of the screen by the TV camera 2. In this case, the image of the person B obtained by the TV camera 2 is coded by the moving image codec 3 and transmitted from the communication control unit 4 to the self-station through the local line 6. Upon receiving the image from the local line 6 via the communication control unit 7, the self-station decodes the received image into the video signal by using the moving image codec 10 and displays the video signal as the FIG. 13 on the TV monitor 12.
When the speaker among the attendants 1 is switched to the person D, the camera operation unit 8 in the self-station is manipulated to transmit a control signal to the camera control device 5, thereby panning the TV camera 2 via a panning means (not shown). Consequently, as shown in FIG. 1B, the person D of the attendants 1 at the conference is imaged at the center of the screen by the TV camera 2. In this case, the image of the person D obtained by the TV camera 2 is transmitted to the self-station via the moving image codec 3, the communication control unit 4, and the local line 6. In the self-station, the video signal is obtained from the local line 6 via the communication control unit 7 and the moving image codec 10 and displayed as the FIG. 13 on the TV monitor 12.
When the speaker among the attendants 1 at the conference is switched to the person A, the camera operation unit 8 in the self-station is manipulated to transmit a control signal to the camera control device 5, thereby panning the TV camera 2. As a result, as shown in FIG. 1C, the person A of the attendants 1 is imaged at the center of the screen by the TV camera 2. In this case, the image of the person A obtained by the TV camera 2 is transmitted to the self-station via the moving image codec 3, the communication control unit 4, and the local line 6. In the self-station, the video signal is obtained from the local line 6 via the communication control unit 7 and the moving image codec 10 and displayed as the FIG. 13 on the TV monitor 12.
As described above, the camera operation unit 8 of the self-station is manipulated to pan the TV camera 2 via the camera control device 5, and so an image in which a speaking one of the attendants 1 at the conference is imaged at the center of the screen can be displayed on the TV monitor 12. Therefore, a speaking one of the attendants 1 in the distant place can be selectively monitored as the FIG. 13 displayed on the TV monitor 12 in the self-station.
The conventional video conference system with the arrangement as described above has the following problems.
That is, various control operations, such as control performed by the operation means in the remote place and control performed by the operation means in the self-station are used to determine the panning position of the TV camera 2, i.e., pan the TV camera 2 toward a particular one of the attendants 1 at the conference in the distant place. If, however, the TV camera 2 is panned to perform switching between persons to be imaged among the attendants 1, this merely results in a change in the FIG. 13 displayed on the TV monitor 12 in the self-station. Therefore, it is difficult for participants in the conference in the self-station to accurately recognize the positional relationship between the attendants 1 in the remote place.
That is, although the attendants 1 at the conference in the distant place are actually seated side by side at different positions, they are displayed at the fixed position of the TV monitor 12 in the self-station. This impairs the ambience of the conference and also causes an inconvenience that the TV camera 2 may be operated in an opposite direction in searching for a specific person by changing the panning position of the TV camera 2 from the self-station.
To eliminate the above inconveniences, there is provided a method of displaying all of the attendants 1 at the conference constantly by using a plurality of TV cameras 2 and a plurality of TV monitors 12 in the self-station. Since, however, this largely increases the quantity of information to be transmitted, the method is impractical when the number of local lines 6 and the installation cost are taken into account.
Although not shown in FIGS. 1A to 1C, the above video conference system further includes a camera for imaging originals, a still image monitor for displaying the images obtained by that camera, and a plotting image input device (e.g., a digitizer) for inputting plotting images.
Each of these devices is used to perform, e.g., writing on a common material image to point out a particular portion.
More specifically, the same material image is displayed on the still image display monitors of terminals of individual participants in a conference, and each participant can perform writing in a given portion of the material image by using the plotting image input device of his or her terminal. This writing is superimposed on the material image displayed on the still image display monitors of all the participants in the conference.
In the conventional video conference system with this arrangement, a participant currently writing data is clearly known if a video conference is held between two stations. If, however, three or more stations are attending at a conference, it is impossible to determine a person currently writing data.